Liquid fuel burning installations



Aug. 8, 1961 l. G. BOWEN ET A].

LIQUID FUEL BURNING INSTALLATIONS Filed Aug. 4, 1958 IDR/s G. BoW

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lNvENToRs ATTORNEL United States Patent Ofiice Patented Aug. 8, 19612,995,185 LIQUID FUEL BURNING INSTALLATIONS Idris Gwynne Bowen,Rolleston-on-Dove, near Burtonon-Trent, and Terence Tyler, Allestree,England, as-

signors to International Combustion (Holdings) Limited, London, England,a British company Filed Aug. 4, 1958, Ser. No. 752,954 Claims priority,application Great Britain Aug. 27, 1957 4 Claims. (Cl. 158-36) Thisinvention relates to liquid fuel burning installations and hasparticular although not exclusive reference to oil fired industrialboiler plants.

In industrial boiler plants, variations of load necessi tate controlover burner heat output and where the liquid fuel flow rates exceedabout gallons per hour it is desirable that the control should be suchthat frequent lighting-up and shutting-down of large burners is avoided.It has been proposed to employ burners whose output can be varied from amaximum down to about 40% of maximum. It has also been proposed to use aburner capable of providing a high output for heavy load conditions anda low output for low load conditions with suitable control apparatus forselecting the required output. Burners of the latter sort may employ asingle, wide range atomiser with a single air register or twin atomisersagain with a single air register. In both cases there is thedisadvantage that combustion conditions under low output are not asfavourable as those for high output.

It is an object of the present invention to provide a liquid fuelburning installation capable of high and low heat outputs underetficient combustion conditions.

Accordingly the present invention provides a liquid fuel burninginstallation comprising a first burner provided with an air register, asecond burner provided with a separate air register, cooling means forsaid second burner, and control means responsive to the load on theinstallation for controlling said second burner, said control means alsocontrolling the supply of air to the separate air register and theoperation of the cooling means.

The first burner has a heat output sufficient for light load conditionswhile the second burner has a heat output which, taken together withthat of the first burner, is sufficient to meet the full load demand ofthe installation. The provision of separate air registers for the twoburners enables each burner to function under optimum combustionconditions and the means for cooling the second burner when it is notoperating avoids overheating of the second burner which might otherwiseoccur when the first burner only is operating.

The second burner and cooling means may comprise a burner of the spilland/or recirculating type wherein the control means reverses the flow offuel through the second burner as the latter is brought into or takenout of operation thereby ensuring the cooling of the burner when it isnot operating. The control means may include a shut-off valve for thesecond burner operated by the pressure difference between a fuel feedline to this burner and a fuel spill line therefrom. The control meansmay also include a valve for controlling the direction of fuel feed flowto the second burner and having a movable element for controlling thesupply of air to the air register of the second burner.

The installation may further comprise further control means responsiveto the load on the installation for starting up and cutting out thefirst burner.

By way of example only, an oil burning installation according to theinvention and suitable for an industrial boiler plant will now bedescribed in greater detail with reference to the accompanying drawingsof which:

FIGURE 1 shows the lay-out of the installation in dia- 'grammatic formonly, and,

FIGURE 2 shows a detail of FIGURE 1 on an enlarged scale.

The drawing shows part of a furnace wall 1 having apertures 2, 3 forreceiving first and second burners 4, 5 respectively and their airregisters 6, 7. The registers are supplied with air under pressure via acommon conduit 8 and are interconnected by a conduit 9 containing anadjustable damper 10.

Oil is fed to the burners 4 and 5 from a feed line 11 via low pressurefilter 12, pump 13, heater 14 and high pressure filter 15. On the outputside of the filter 15, the feed line 11 divides and a branch line 16 isconnected to the burner 4 via a thermostatically controlled isolatingvalve 17. Line 11 is, on the output side of filter 15, connected to acontrol valve 18 for controlling the flow of oil to the second burner 5.Flow lines 19 and 20 connect the valve 18 with the burner 5.

The control valve 18 comprises a piston-like member 21 movable in acylinder 22 against a helical spring 23. The member 21 has peripheralchannels 24, 25 located between end flanges 26 and separated by flange27. Channel 25 is connected by a drilling 28 with the space in thecylinder at one end of the member 21. Connections are made to the valve18 in the positions shown in the drawing so that with the member 21 inthe position shown, oil from line 11 passes via channel 24 to flow line19 and the burner 5 and thence via fiow line 20 back to the valve 18. Itwill be seen that the flow line 20 is connected at two points to thevalve 18 and in the left-hand drawing one of these points is closed bythe flange 26. A by-pass line 29 connects together spaces at each end ofthe cylinder and flow along the line 29 is controlled by athermostatically operated isolating valve 30'. Oil is finally returnedto a low pressure source via line 31.

Valve 17 is controlled by means of a thermostat (not shown) situated inthe waterways of a boiler (not shown) fired by the installation. Thethermostat is connected to valve 17 by means of line 17a.

Valve 30 is controlled by means of a second thermostat (not shown)situated immediately below the first mentioned thermostat in the boilerwaterways. The second thermostat is set to operate at a lowertemperature than the first mentioned thermostat and is connected tovalve 30 by means of a line 30a.

Burner 5 is of the spill or recirculating type and oil from line 19passes via a central passageway 32 in an inner tube 33 to a swirlchamber 34 and from thence through spill apertures 35 and an annularpassage 36 to the flow line 20. With oil flow in the direction justdescribed, a movable piston 37 in the burner 5 is held in the positionshown in the drawing by the pressure difierence between the lines 19 and20 acting across the piston 37. Connected for movement with the piston37 is a lance cut-off valve 38 whose tip closes the outlet orifice 39 ofthe burner 5.

The movable member 21 is connected by a suitable linkage to the damper10 positioned in the interconnecting conduit 9 referred to above.

Automatically operating ignition means indicated at 40 are providedadjacent burner 4 and their operation is initiated each time valve 17 isopened.

In use, the installation operates on low load conditions with burner 4only firing. The first mentioned thermostat operates to open or closevalve 17 as the waterway temperature respectively falls below or exceedsthat set for the operation of the thermostat, ignition means 40 beinginitiated with the opening of valve 17. The moving parts are in thepositions shown, the orifice 39 being closed also the damper 10.Isolating valve 30 is open and oil from the spill line of burner 5circulates freely to the low pressure source of oil.

Burner 5 is brought into operation when the waterway temperature dropsbelow that governing the second thermostat; the isolating valve 30closes causing pressure to build up which forces the element '21 to theleft as seen in FIG. 1 a distance x against the compression of helicalspring 23. Oil from the feed line, 11 now passes via channel 24 to flowline 20 and the reversal of the differential pressure across piston 37withdraws the tip of the lance cut-off valve 38 from the orifice 39 ofburner 5. Oil can now pass from the swirl chamber 34 through the orifice39 where it is ignited by the flame already issuing from burner 4. Atthe same time damper is moved to an open position thus permitting airflow to air register 7.

The reverse procedure occurs when the waterway temperature exceeds thatset to control the second thermostat, and burner 5 is shut down.

By suitable choice of the heat outputs of the burners 4 and 5 it ispossible to operate the installation for long periods withoutextinguishing burner 4. Burner 4 is shut down by valve 17 only afterburner 5 has been shut down by valve 30-, which is closed by itscontrolling thermostat at a lower temperature.

The separate air registers 6 and 7 enable both burners to operate underoptimum combustion conditions. The use of high atomising pressures andair turbulence enables the flames of the burners to be smaller than inexisting installations.

If this installation is used to burn heavy oils, the small burner 4 maybe warmed before ignition, that is, during the start-up period, by thecirculation of oil passing to or from the isolation valve 30 from an oilheater (not shown).

The thermostats controlling the operation of the; installation can bereplaced by any suitable control devices which are responsive to changesin temperature or pressure.

We claim:

1. A liquid fuel burning installation comprising a low thermal outputliquid fuel burner, a first air register surrounding said low outputburner, a liquid fuel igniter with ignition electrodes located adjacentsaid low thermal output burner only, a supplementary high thermal outputliquid fuel burner of the spill recirculating type, a second airregister surrounding said high output burner, said high thermal outputburner being adjacent said low thermal output burner, liquid fuel flowand return pipes connected to said burners, a liquid fuel flow controlvalve in the flow pipe to said high output burner only whereby the flowto the latter is controllable between cooling and operative conditions,a conduit joining said first and second air registers, an air fiowcontrol element in said conduit, a linkage joining said liquid flowcontrol valve to said air flow control element closing the latter whenthe fuel flow to said high output burner is in said cooling conditionand means responsive to the load on the installation for controlling theoperation of said high thermal output burner only lighting of which isby means of said low thermal output burner.

2. A liquid fuel burning installation comprising a low thermal outputliquid fuel burner, a first air register surrounding said low outputburner, liquid fuel igniter with ignition electrodes located adjacentsaid low thermal output burner only, a supplementary high thermal outputliquid fuel burner of the spill recirculating type, a second airregister surrounding said high output burner, said high thermal outputburner being adjacent said low thermal output burner, liquid fuel flowand return pipes connected to said burners, a liquid fuel flow controlvalve in the flow pipe to said high output burner, said valve comprisinga cylinder and a flow controlling piston movable within said cylinderwhereby the flow in said flow pipe is controllable between cooling andoperative conditions, a conduit joining said first and second airregisters, an air flow control element in said conduit, a linkagejoining said liquid flow control valve to said air flow control elementclosing the latter when the fuel flow to said high output burner is insaid cooling condition and means responsive to the load on theinstallation for controlling the operation of said high thermal outputburner only lighting of which is by means of said low thermal outputburner.

3. A liquid fuel burning installation comprising in combination a lowthermal output liquid fuel burner, a first air register for said lowoutput burner, a liquid fuel igniter with ignition electrodes locatedadjacent said low thermal output burner only, a supplementary highthermal output liquid fuel burner of the spill recirculating type, asecond air register for said high output burner, said high thermaloutput burner being adjacent said low thermal output burner, fuel flowand return pipes connected to said burners, a liquid fuel flow controlvalve in the fuel flow pipe to said high output burner whereby the flowto the latter is controllable between cooling and operative conditions,air flow control means located in said second air register, a linkageinterconnecting said control valve and said air flow control means, anda device responsive to the thermal load on the installation foroperating said control valve to control the operation of said highthermal output burner only.

4. A liquid fuel burning installation comprising a low thermal outputliquid fuel burner, a first air register surrounding said low outputburner, a liquid fuel igniter with ignition electrodes located adjacentsaid low thermal output burner only, a supplementary high thermal outputliquid fuel burner of the spill recirculating type, a second airregister surrounding said high output burner, said high thermal outputburner being adjacent said low thermal output burner, liquid fuel flowand return pipes connected to said burners, a liquid fuel flow controlvalve in the flow pipe to said high output burner, said valve comprisinga cylinder and a flow controlling piston movable Within said cylinder,bias means for urging said piston into a position in which fuel flow tosaid second burner flows therethrough in a cooling circuit, a liquidfuel by-pass passage connected in parallel with said piston, a liquidfuel flow control valve in said by-pass passage, a device responsive tothe thermal load on the installation for operating said control valve insaid by-pass passage whereby said piston is movable against said biasmeans into a position in which fuel flow to said second burner flowstherethrough in a fuel burning circuit, an air flow control element insaid second air register and a linkage joining said piston to said aircontrol element.

References Cited in the file of this patent UNITED STATES PATENTS1,637,820 Hawkins Aug. 2, 1927 2,150,113 Wunsch et al Mar. 7, 19392,743,137 Wilson Aug. 24, 1956 2,519,240 Fellows Aug. 15, 1950

